use relative position instead of angle; need to change the comments and the documentation

Project/Assets/ML-Agents/Examples/Sorter/Scripts/SorterAgent.cs

             // The first 20 are one hot encoding of the value of the tile
             // The 21st is the angle of the tile on the circle wall
             // The 22nd is a boolean : 1 if the tile was visited already and 0 otherwise
-            float[] listObservation = new float[k_HighestTileValue + 2];
+            float[] listObservation = new float[k_HighestTileValue + 3];
-            listObservation[k_HighestTileValue] = (item.transform.localRotation.eulerAngles.y / 360f);
-            listObservation[k_HighestTileValue + 1] = item.IsVisited ? 1.0f : 0.0f;
+            var tileTransform = item.transform.GetChild(1);
+            listObservation[k_HighestTileValue] = (tileTransform.position.x - transform.position.x) / 20f;
+            listObservation[k_HighestTileValue + 1] = (tileTransform.position.z - transform.position.z) / 20f;
+            // listObservation[k_HighestTileValue] = (item.transform.localRotation.eulerAngles.y / 360f);
+            listObservation[k_HighestTileValue + 2] = item.IsVisited ? 1.0f : 0.0f;
             // Here, the observation for the tile is added to the BufferSensor
             m_BufferSensor.AppendObservation(listObservation);